The Active Matrix Organic Light-Emitting Diode (AMOLED) display panels have advantages such as short response times, high display brightness levels, high display contrasts, and low power consumption levels. It is also easier to produce transparent and flexible AMOLED display panels. The AMOLED display technology is often regarded as a main stream display technology. Nowadays, development efforts have promoted the mass production of AMOLED display panels.
Pixel array formed by active matrix or Thin Film Transistors (TFTs) is a key component of the AMOLED display technology. In existing AMOLED display technologies, amorphous-silicon TFTs, low-temperature poly-silicon TFTs, organic semiconductor TFTs, and certain metal oxide TFTs are often used to drive the pixels that form the pixel array. However, problems or defects related to TFT threshold voltage shifts and threshold voltage non-uniformity may exist in the existing AMOLED display technologies. As a result, when driving organic light-emitting diode (OLED) pixels, an existing TFT array may not be able to provide stable and/or uniform driving currents. The display quality of the corresponding AMOLED display panel may therefore be adversely affected.
To solve the problems mentioned in the existing AMOLED display technologies, pixel circuits for compensating the threshold voltage shifts and threshold voltage non-uniformity have been developed. Until now, many of the developed pixel circuits have an undesirably large number of TFTs and/or control signal lines, which may occupy an undesirably large area on the circuit board and limit the aperture ratio of the display panel. Improvements on the display resolution may be limited. On the other hand, the pixel driving circuits with fewer TFTs (e.g., 2 or 3 TFTs) often require relatively complex control in timing, making it difficult to implement peripheral driving in the display panel.